Digital lighting technologies such as light-emitting diodes (LEDs) offer significant advantages over incandescent and fluorescent lamps. These advantages include, but are not limited to, better lighting quality, longer operating life, and lower energy consumption. LEDs also are being designed to have more desirable color temperatures than do traditional lamps. Moreover, LEDs do not contain mercury or any other toxic substance. Consequently, a market exists for LED-based lamps as retrofits for legacy lighting fixtures.
A number of design challenges and costs are associated with replacing traditional lamps with LED illumination devices. These design challenges include thermal management, installation ease, and manufacturing cost control.
Thermal management describes a system's ability to draw heat away from an LED. Lighting technology that employs LEDs suffers shortened lamp and fixture life and decreased performance when operating in high-heat environments. Moreover, when operating in a space-limited enclosure with limited ventilation, such as, for example, a can light fixture, the heat generated by an LED and its attending circuitry itself can cause damage to the LED.
Cooling systems for lighting devices have traditionally employed passive cooling technology, such as a heat sink thermally coupled to a lighting device. In some other systems, a fan has also been employed to direct a flow of air through the heat sink, thereby accelerating the dissipation of heat from the heat sink and, therefore, from the lighting device. A heat sink may be used to transfer heat from a solid material to a fluid medium such as, for example, air. One of the challenges in using a heat sink, however, is that of absorbing and dissipating heat at a sufficient rate with respect to the amount of heat being generated by the LED. If the heat sink does not have the optimal amount of capacity, the heat can gradually build up behind the LED and cause damage to the components.
Compared to incandescent and fluorescent lamps, LED-based lighting solutions have relatively high manufacturing and component costs. These costs are often compounded by a need to replace or reconfigure a light fixture that is designed to support incandescent or fluorescent lamps to instead support LEDs. Consequently, the cost of adoption of digital lighting technology, particularly in the consumer household market, is driven by design choices for retrofit LED-based lamps that impact both cost of manufacture and ease of installation.
Traditional cooling systems for lighting devices have also relied upon a supply of air from the environment to blow onto and transfer heat away from the lighting device. As a result, proposed solutions in the prior art have included vents, apertures, or other openings generally in the housing of the lighting device to provide a supply of cool air from the environment.
The introduction of air from the environment into the housing of a lighting device may also result in the introduction of contaminants. Substances carried along with the environmental air can inhibit and impair the operation of the lighting device, causing faulty performance by, or early failure of, the digital device. Moreover, the accumulation of contaminants in the cooling system can result in a reduction in efficacy of the cooling system. Accordingly, there is a need in the art for a cooling system that can operate in a system sealed from the environment, hence without a supply of air external to the sealed system.
Sealed cooling systems are known in the art. As an example, a Peltier device can be used to cool a digital system without a supply of external air. However, Peltier devices are expensive to produce and use electricity inefficiently in comparison to more traditional cooling systems. Accordingly, there is a need for a cooling system in a sealed environment that is inexpensive to produce and is energy efficient.
Other proposed solutions have included the use of a sealed system containing a fluid thermally coupled to a digital device in association with a radiator where fluid warmed by the digital device radiates the heat into the environment. However, these systems require significant amounts of space in order to pipe the fluid between the radiator and the thermal coupling with the digital device. Accordingly, there is a need for a cooling system that can operate in a space-limited sealed system.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.